Rotary electrode assembly



March 23, 1954 M. M. SEELOFF ET AL ROTARY ELECTRODE ASSEMBLY Filed NOV.30, 1951 ATTORNEY Patented Mar. 23, 1954 ROTARY ELECTRODE ASSEMBLYMelvin M. Seelofl and Joseph H. Cooper, Warren,

Ohio, assignors to The Taylor-Wineld Corporation, Warren, Ohio, acorporation of Ohio ApplicationNovember 30, 1951, Serial No. 259,167

9 Claims. 1

The present invention relates to an improved arrangement for conductingelectric current between relatively moving conductor parts and findsparticularly advantageous application where high current loads must beso conducted, as for example, in electric resistance welding.

It is an object of the present invention to pyrovide a novel rotary typeelectrode assembly, particularly for use in electric resistance seamwelding apparatus, having certain novel features of construction wherebyelectric current may be passed between the stationary and movableconductor members of the assembly with a minimum of loss lof power dueto contact resistance. Inherently accruing from such provision of lowresistance contact between the movable and stationary members areincreased operating life of such contact members and lesser coolingrequirements as will be understood.

More particularly, a further object of the present invention isl toprovide a novel rotary electrode assembly wherein the rotary contactmember is supported. by means wholly independent of and electricallyisolated from the contact path of the electric current passing throughthe assembly. In accordance with this object we may provide suitableanti-friction means for rotatably journaling the movable member of theelectrode assembly whereby frictional resistance to movement of themovable electrode member is maintained at a minimum and. mechanicalimpedance to movement of the electrode over the work or the work pastthe electrode is accordingly kept at a practical minimum. In addition toreduced rictional impedance the arrangement herein proposed providesthat pressure applied to the electrode assembly in a directiontransverse to the-axis of rotation of the movable member will beitotallyabsorbed in the anti-friction journaling means whereby uneven contactpressures between the relatively movable Contact members are eliminatedand the operatingv life thereof is proportionately increased. Further,our construction isl such that while the rotary electrode is rigidlyrsupported and may be moved or guided with precision in an assemblywelding machine, the current-conducting assembly presents. minimum.interference with the welding throat space in. the machine. The assemblyis made up of relatively fewl partsA and includes a simple arrangementfor adjusting the contact. pressure betweenlthel` relatively movableparts' of. the, assembly.

AAnotherobject. of thepresentl invention is the provision of!- ay novel*rotaryy electrode assemblyhaving the above set forth characteristicswhich is, in addition, totally enclosed about the relatively movablecontact members whereby the same may be maintained in a bath oflubricating fluid, as for example castor oil, to thus providesubstantially frictionless relative movement between such contactmembers and to provide additional advantageous characteristics, as forexample, improved electrical contact and improved cooling of the parts.

Another object of this invention is the provision in a rotary electrodeassembly of the character described of certain provisions whereby theadvantageous low resistance and long operating life characteristics arerelatively unaffected by, for example, deflection of the anti-frictionjournaling means undery operating pressure tending to alter the originalalignment of the rotary member.

Other objects andl advantages of the invention will become apparent uponfull consideration of the following detailed specication andaccompanying drawing wherein is illustrated a preferred embodiment ofthe invention.

In the drawing:

Figure 1 is an axial cross section of a rotary welding electrodeassembly constructed in accordance with the teachings of our invention,

showing particularly the general arrangement ofA the anti-frictionjournaling means and contact members; and

Figure 2 is a cross sectional view taken along line II-II of Figure lshowing details of the contact members or brushes constructed in accordgance with the principles of the invention.

In Figure 1 the reference numeral ill designates a mounting member whichmay be associated with suitable means, not shown, for effecting verticalmovement of the electrode assembly and' for applying pressure during awelding operationv as will be understood. Mounted rigidly to the mem-v4ber l0 by bolts Il, but preferably electrically isolated rom the memberl D by means of insulators i2 and i3, is a body member I 4, of suitablecurrent conductive material, which cooperatively serves to conductcurrent from a source, not shown, and to house contact brushes l5 and I6and anti-friction bearings Il and I8 as will appear. Bearings Il and I8are mounted in the body member Hi in spacedr axially aligned relation asshown in Figure 1 and are electrically insulated from the housing lll bymeans of insulating members i9 and 26.

The said insulating members i9 and 2Q are preferably of non-resilient 3material to avoid excessive deformation under operating load as will beunderstood.

J ournaled by the bearings I1 and Iii, which are preferably of thetapered roller type as illustrated, is a current conductive electrodespindle 2| having, in accordance with usual practice, internal passagestherein, as at 22, for providing a continuous flow of cooling medium.The spindle 2| is provided at its forward end with a shoulder 23 whichabuts against the bearing i1, and is threaded at its opposite endportion 24 to receive a nut 25. As shown, the inner or left hand endface of the nut 25 bears against the bearing I8, and it will beunderstood that by suitable axial adjustment of the nut 25 the spindle2| may be rmly restrained against any longitudinal movement with respectto the body member I4. A conventional electrode wheel 2E is secured tothe outer end of the spindle 2 I, and the wheel 26 may be provided withsuitable cooling passages, not shown, communicating with the passage 22.

As shown in Figure 2, the upper portion 21 of the housing I4 is providedwith a downwardly depending ridge 28 disposed generally parallel to thespindle 2| and having accurately machined substantially vertically sidewall surfaces 2t and 30 thereon. To carry current from the member I4 tothe rotating spindle 2| we have provided a pair of rigid contact brushesI and It of suitable current conducting material and having contactsurfaces 3| and 32 at each the upper and lower portions thereof forcontacting respectively the side wall surfaces 29 and 30 and the spindle2|. The contact surfaces 32, preferably of silver, are arcuately shapedto conform with the contour of the spindle 2|, and in the embodimentshown contact by each surface 32 with the spindle 2| is madecircumferentially over an arc in the order of 90 degrees andlongitudinally over a substantial portion of the distance between thebearings |1 and I8. Contact surfaces 3|, also preferably of silver, arearcuately shaped to a small degree and are adapted to have contact withthe side wall surfaces 29 and 30 in the manner shown. The arcuatecontours of the surfaces 3| provide that substantially the same contactis made between the surfaces 3| and the side walls 29 and 30 regardlessof slight angular deviations of the contact brushes I5 and i6 such as,for example, would occur as the contact surfaces 32 become worn throughprolonged use.

To hold the brushes I5 and I6 properly in contact with the spindle 2|and side wall surfaces 29 and 3S we provide a bolt 33 which is receivedin apertures 34 in each of the brushes i5 and i6; the said aperturesbeing located substantially centrally between the spindle 2| and ridgeportion 21 as shown. The head 35 of the bolt 34 bears, through washers36 and 31 against the outer side wall of the contact brush I5, and tosimilarly bear against the outer side wall of brush I6 we provide acompressible coil spring 38, washer 39 and nut 40. Washers 36 and 31 areprovided with complementary arcuate adjoining surfaces whereby pressureexerted thereon by the bolt 34 will be evenly applied to the Contactbrush I5 regardless of slight angular deviations of the said brush I5with the bolt as the surfaces 32 become worn.

The above described combination of brushes I5 and I6 and the particularmeans for returning the same in proper contact with the spindle 2| andside wall surfaces 29 and 3|) forms an important part of the presentinvention, and it should be particularly observed that by this ar- 4rangement the brushes I5 and I6, when positioned in contact with thespindle 2| and resiliently clamped by means of the bolt 34 and spring38, inherently make the proper contact with the side wall surfaces 29and 30 and retain such contact even though the contact surfaces 32 weardown and cause the brushes I5 and I6 to angle inwardly at their lowerends. It may also be observed that, with the exception of the radius ofthe arcuate surfaces 32 there are no critical dimensions which must bemet in making the brushes I5 and I6, nor is the distance between thevertical side wall surfaces 29 and 35 at all critical; it beingunderstood that the mere clamping of the Said brushes I5 and I6 aboutthe spindle 2| will inherently cause proper contact to be made at allpoints.

To provide lubrication for the contact surfaces 32 and the bearings i1and I8 we prefer to enclose the said components in a fluid-tight housingand to maintain in said housing a bath of lubricating fluid, as forexample castor oil, which is accordingly continuously applied to themoving parts to lubricate the same and which, in addition, serves toprovide improved electrical contact between the various contact surfacesand to aid in removing the heat therefrom as will be understood.

An enclosed housing for the above mentioned purpose is formed bysuitably securing side walls 4I and 4Z to the member I4 as shown inFigure 2. The forward end of the housing is sealed by providing aresilient annular sealing member 43 positioned forwardly of the bearingI1 and` extending from the member I4 into resilient contact with thespindle 2 I. At the opposite end of the housing we provide a cap member44 which is secured to the member I4 by means of bolts 45. Extendingbetween the cap member 44 and the spindle 2| near the end thereof is aresilient annular sealing member 46 which is operative to seal the righthand end of the housing in a fluidtight manner as desired in accordancewith the objects of this invention.

Shown in Figure 2 are filling and draining ports 41 and 48 respectivelythrough which the housing may be properly maintained with a lubricatingbath, and it will be understood that such lubricating bath may, ifdesired, be circulated throughout the housing by connecting suitablepump means, not shown, to the ports 4l' and 48.

In the embodiment herein illustrated cooling medium for the spindle 2|is admitted into the passage 22 through a conduit member 49 which issecured in the cap member 44 and extends into the passage 22 in spacedconcentric relation thereto. The flow of the medium is thus inwardlythrough the conduit 49 and outwardly through the annular space providedbetween the conduit 49 and the side walls of the passage 22. An outletfor the medium is provided by a port 50 in the cap member 44 as shown inFigure l. In accordance with usual practice we also provide means forcooling the main housing of the assembly and this may be conventionallyaccomplished -by providing a plurality of interconnected passages 5| inthe member I4 and side walls 4I and 42 having suitable inlet and outletports, not shown, whereby the passages 5| may be connected with a sourceof cooling medium, also not shown.

It should now be apparent that we have accomplished the objectsinitially set forth. The rotary electrode assembly disclosed hereinincorporates certain ncvel features of construction which: lend-rgenerally-to anarrangement whereby av rotary electrode-supportingspindle may be ro'- tatably supported by means both structurally andvelectrically independent of the means for transferring the electricalcurrent from theA stationary conductor member to the rotating spindle,and particularly to a wholly practical and mechanicallyv simplifiedarrangement for accomplishing the above general construction. It should`bev noted. particularly that the electrode is rigidly supported bothaxially and radially and that the movable contact assembly provideslarge currentconducting surfaces which, however, dov not extend tothelower surface of the electrode-carrying shaft so that there is a minimumof interference with the welding throat clearance in the assembledwelding machine.

In the apparatus according to our invention we have provided a novelarrangement, including a pair of brushes I5 and i6 and ridge portion 21of current conductive member le, for conducting current from the ridgeportion 2l to the spindle 2I which may be quickly and easily assembledby clamping the said brushes I5 and i6 on opposite sides of the spindle2| and ridge portion 21 with a single clamping device, as for examplethe bolt 331 and coil spring 38 illustrated. With the brushes I5 and I6so clamped the concave lower contact surfaces 32 thereof inherentlyassume the proper position relative to the spindle 2'I whereby an evencontact pressure is assured over the entire contact surface and thecurrent is accordingly distributed evenly as is desired for minimumresistance to current flow and long operational life and otheradvantages as will be understood. At the upper point of contact we haveprovided each of the brushes I5 and I6 with a convex contact surface 3iwhich is adapted tobear against a ilat` substantially vertical machinedsurface 29 or 30, and it will be observedthat as the lower Contactsurfaces 32 become worn through use, causing the brushes I5 and I Ii toangle slightly inwardly, the upper contact surfaces 3-I will merely rollover the flat surfaces 29 and 3l] and maintain substantially the samearea contact therewith whereby the advantageous electricalcharacteristics of the assembly are retained. It will also be apparentthat the effectiveness of the assembly herein described is substantiallyunaffected by expansion and contraction of the parts as may occur duringa welding or other current conducting operation since the convex contactsurfaces 3| may slide freely along the fiat side wall surfaces-29 and 3@to absorb any uneven expansion and contraction.

Our construction is further advantageous in that it readily lends-itself to the provision of a lubricant bath about the contact surfaces32 whereby the frictional wear is reduced to a minimum, and also wherebyheat may be more readily carried away from. the point of Contact as willbe understood.

In addition to the various electrical and structural advantages inherentin our electrode assembly it will be noted that the overall constructionis one of utter simplicity, both in regard to the initial. manufactureand assembly of the parts and in. regard to such maintenance as maysubsequently be required. The brushes I 5 and I6 may be readily replacedwhen necessary and it will be noted that interchangeability of suchbrushes may be provided without undue regard to manufacturingtolerances. These features contribute materially to lowering the costsof the product as will be readily understood.

Having thus shown and specifically described av preferred form of ourinvention, what we claimv as new and desire to secure by LettersPatentis:

l. In a rotary electrode assembly of the type having a housing, spacedanti-friction bearings in said housing, a current conductive spindleriournaled by said bearings, and contact means for transferringelectrical current fromv said housing to said spindle; the improvementin such assembly comprising a ridge portion on said body memberdepending downwardly therefrom and disposed above and parallel to saidspindle and located intermediate said bearings, said ridge portionhaving flat substantially vertical side wall surfaces thereon, saidcontact means comprising a pair ofcurrent conductive brushes disposedoneon` each side of said ridge portion in contact therewith andextending downwardly into contact with said spindle, said brushes havingupper and lower contact surfaces thereon adapted to contact respectivelysaid ridge portion and' said spindle, said lower contact surfaces havingcontours complementary to those of said spindle, said upper contactsurfaces being of convex con'- tour and adapted to bear against saidflat side wall surfaces of said ridge portion, a bolt extendingtransversely through said brushes intermedi'- ato said spindle and saidridge portion, and spring means positioned over said bolt and adapted incombination with said bolt to yieldably draw said brushes together.

2. In a rotary electrode assembly of the type having a housing, spacedanti-friction bearings in said housing, a current conductive spindlejournaled by said bearings, and contact means for transferringelectrical current from said housing to said spindle; the improvement insuch assembly comprising a ridge portion on said body member dependingdownwardly therefrom and disposed above and parallell to said spindleand located intermediate said bearings, said ridge portion having iiatsubstantially vertical side wall surfaces thereon, said contact meanscomprising a pair of current conductive brushes disposed one on eachside of said ridge portion in contact. therewith and extendingdownwardly into contact with said spindle, said brushes having upper andlower contact surfaces thereon adapted to Contact respectively saidridge portion and said' spindle, said lower contact surfaces havingcontours complementary to those of said spindle, said upper contactsurfaces being of convex oontour and adapted to bear against said datside wall surfaces of said ridge portion, resilient means acting on saidbrushes intermediate said spindle and said ridge portion adapted to urgesaid brushes into contact with said spindle and said ridge portion.

3. In a rotary electrode assembly of the type having a housing, spacedanti-friction bearings in said housing, a current conductive spindlejournaled by said bearings, and contact means for transferringelectrical `current from said housing to said spindle; the improvementin such assembly comprising a ridge portion on said body memberdepending downwardly therefrom and disposed above and parallel to saidspindle and located intermediate said bearings, said ridge portionhaving side wall surfaces thereon, said contact means comprising a pairof current conductive brushes disposed one on each side of said ridgeportion in contact with the side wall surfaces thereon and extendingdownwardly into contact with said spindle, said brushes having upper andlower contact surfaces thereon adapted to contact respectively saidridge portion and said spindle, said upper contact surface beingsubstantially in line contact with said side wall surfaces along a lineparallel with said spindle, one of said last mentioned surfaces being ofconvex contour whereby said line contact is maintained regardless ofangular movement of said brushes about the axis of said line, andresilient means acting upon said brushes adapted to urge said brushesinto Contact with said side wall surfaces and said spindle.

4. In a rotary electrode assembly or the type having a housing, spacedanti-friction bearings in said housing, a current conductive spindlejournaled by said bearings, and contact means for transferringelectrical current to said spindle; the improvement comprising a portionon said body member having a pair of current conductive side wallsurfaces disposed parallel to said spindle, said contact meanscomprising a pair of current conductive brushes disposed one on eachside of said spindle in contact therewith and each in contact with aside wall surface, said brushes having upper contact surfaces adapted tocontact said side wall .surfaces substantially along a line, one of saidlast-mentioned surfaces being generally of convex contour whereby saidsurfaces remain in contact substantially on a line regardless of angularmovement of said brushes about the axis of said line, and resilientmeans adapted to urge said brushes into contact with said spindle andsaid side wall surfaces.

5. Apparatus according to claim 4 further characterized by said pair ofcurrent conductive side wall surfaces facing away from each other; andsaid resilient means including a bolt member extending through saidbrushes intermediate said spindle and said side wall surfaces, and aspring member adapted in combination with said bolt member to yieldablyforce said brushes together whereby the same are urged into pressurecontact with said side wall surfaces and said spindle.

6. In a rotary electrode assembly of the type having a body member,spaced anti-friction bearings mounted in said member, a currentconductive spindle journaled in said bearings, a relatively fixedcurrent conductor, and contact means for transferring current from saidfixed conductor to said spindle; the improvement in such assemblycharacterized by said relatively fixed current conductor being spacedfrom said. spindle and having side wall surfaces disposed parallel tosaid spindle, and by said contact means comprising a pair of currentconductive brush members positioned each in contact with a side wallsurface and extending into contact with said spindle, said brush membersbeing in contact with opposite sides of said spindle, said brush membershaving upper contact surfaces thereon adapted to make line contact withsaid side wall surfaces along a line parallel with said spindle, one ofsaid last-mentioned surfaces being of convex contour whereby said lineContact is maintained regardless of angular movement of said brushmembers about the axis of said line, and yieldable means actingcooperatively upon each of said brush members adapted to urge saidmembers into pressure contact with said spindle and said side wallsurfaces.

7. Apparatus according to claim 6 further characterized by said currentconductive portion being located intermediate said bearings, side wallmembers secured to said body member and forming in combination therewitha substantially enclosed housing, and sealing means extending betweensaid housing and said spindle externally of said bearings for renderingsaid housing uid tight for the reception of a liquid lubricant bathabout said bearings and said spindle.

8. In a rotary electrode assembly of the type having a body member,bearings mounted in said member, a current conductive spindle journaledin said bearings, a relatively xed current conductor, and contact meansfor transferring current from said iixed conductor to said spindle; theimprovement in such apparatus characterized by said fixed currentconductor having an exposed surface portion, and by said contact meanscomprising a current conductive brush having a pair of contact surfacesadapted to contact respectively said spindle and said exposed surfaceportion, and resilient means for urging said brush simultaneously intocontact with said surface portion and said spindle, said surface portionmaking substantial line contact with said brush along an axis parallelwith said spindle whereby relatively uniform contact may be maintainedregardless of angular movement of said brush about the axis of saidline.

9. Apparatus according to claim 8 further characterized by saidrelatively xed conductor comprising a ridge portion of said body member,said ridge portion disposed parallel to said spindle and locatedintermediate said bearings, and said brush contacting said spindleintermediate said bearings.

MELVTN M. SEELOFF. JOSEPH H. COOPER.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 1,910,882 Caputo 1 May 23, 1933 2,006,835 Kurtze July 2, 19352,529,634 Sciaky Nov. 14, 1950

